linker script: Remove KEEP from RAM-resident sections

Reduce RAM usage when not all data/bss sections in source files were used.

components/esp32/ld/esp32.common.ld

@@ -99,7 +99,7 @@ SECTIONS
     *(.sbss2.*)
     *(.gnu.linkonce.sb2.*)
     *(.dynbss)
-    KEEP(*(.bss))
+    *(.bss)
     *(.bss.*)
     *(.share.mem)
     *(.gnu.linkonce.b.*)
@@ -111,17 +111,17 @@ SECTIONS
   .dram0.data :
   {
     _data_start = ABSOLUTE(.);
-    KEEP(*(.data))
-    KEEP(*(.data.*))
-    KEEP(*(.gnu.linkonce.d.*))
-    KEEP(*(.data1))
-    KEEP(*(.sdata))
-    KEEP(*(.sdata.*))
-    KEEP(*(.gnu.linkonce.s.*))
-    KEEP(*(.sdata2))
-    KEEP(*(.sdata2.*))
-    KEEP(*(.gnu.linkonce.s2.*))
-    KEEP(*(.jcr))
+    *(.data)
+    *(.data.*)
+    *(.gnu.linkonce.d.*)
+    *(.data1)
+    *(.sdata)
+    *(.sdata.*)
+    *(.gnu.linkonce.s.*)
+    *(.sdata2)
+    *(.sdata2.*)
+    *(.gnu.linkonce.s2.*)
+    *(.jcr)
     *(.dram1 .dram1.*)
     *libesp32.a:panic.o(.rodata .rodata.*)
     _data_end = ABSOLUTE(.);